1 //===- Interpreter.cpp - Top-Level LLVM Interpreter Implementation --------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the top-level functionality for the LLVM interpreter.
11 // This interpreter is designed to be a very simple, portable, inefficient
12 // interpreter.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "Interpreter.h"
17 #include "llvm/CodeGen/IntrinsicLowering.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Module.h"
20 #include "llvm/ModuleProvider.h"
21 #include <cstring>
22 using namespace llvm;
23 
24 namespace {
25 
26 static struct RegisterInterp {
27   RegisterInterp() { Interpreter::Register(); }
28 } InterpRegistrator;
29 
30 }
31 
32 extern "C" void LLVMLinkInInterpreter() { }
33 
34 /// create - Create a new interpreter object.  This can never fail.
35 ///
36 ExecutionEngine *Interpreter::create(ModuleProvider *MP, std::string* ErrStr,
37                                      CodeGenOpt::Level OptLevel /*unused*/) {
38   // Tell this ModuleProvide to materialize and release the module
39   if (!MP->materializeModule(ErrStr))
40     // We got an error, just return 0
41     return 0;
42 
43   return new Interpreter(MP);
44 }
45 
46 //===----------------------------------------------------------------------===//
47 // Interpreter ctor - Initialize stuff
48 //
49 Interpreter::Interpreter(ModuleProvider *M)
50   : ExecutionEngine(M), TD(M->getModule()) {
51 
52   memset(&ExitValue.Untyped, 0, sizeof(ExitValue.Untyped));
53   setTargetData(&TD);
54   // Initialize the "backend"
55   initializeExecutionEngine();
56   initializeExternalFunctions();
57   emitGlobals();
58 
59   IL = new IntrinsicLowering(TD);
60 }
61 
62 Interpreter::~Interpreter() {
63   delete IL;
64 }
65 
66 void Interpreter::runAtExitHandlers () {
67   while (!AtExitHandlers.empty()) {
68     callFunction(AtExitHandlers.back(), std::vector<GenericValue>());
69     AtExitHandlers.pop_back();
70     run();
71   }
72 }
73 
74 /// run - Start execution with the specified function and arguments.
75 ///
76 GenericValue
77 Interpreter::runFunction(Function *F,
78                          const std::vector<GenericValue> &ArgValues) {
79   assert (F && "Function *F was null at entry to run()");
80 
81   // Try extra hard not to pass extra args to a function that isn't
82   // expecting them.  C programmers frequently bend the rules and
83   // declare main() with fewer parameters than it actually gets
84   // passed, and the interpreter barfs if you pass a function more
85   // parameters than it is declared to take. This does not attempt to
86   // take into account gratuitous differences in declared types,
87   // though.
88   std::vector<GenericValue> ActualArgs;
89   const unsigned ArgCount = F->getFunctionType()->getNumParams();
90   for (unsigned i = 0; i < ArgCount; ++i)
91     ActualArgs.push_back(ArgValues[i]);
92 
93   // Set up the function call.
94   callFunction(F, ActualArgs);
95 
96   // Start executing the function.
97   run();
98 
99   return ExitValue;
100 }
101 
102